Rotary drum limit switch operating mechanism



W. P. WEGLARZ ROTARY DRUM LIMIT SWITCH OPERATING MECHANISM Filed Fb. 25,1957 June 24, 1958 2 Sheets-Sheet 1 FICH 1N VENTOR foliar Q Weglclr A.l. 4 Noooooooooooorwluoo. 00000191600@@Mn Mm I@ MMR ATTORNEY June 24,1958 w. i5. wEGLARz ROTARY DRUM LIMIT swITca OPERATING MECHANISM ImaFeb.

2 Sheets-Sheet 2 INVENTOR Woler P. Weglar WM. www

ATTORNEY United States Patent C) ROTARY DRUM LIMIT SWITCH OPERATINGMECHANISM Walter P. Weglarz, Philadelphia, Pa., assignor to The BuddCompany, Philadelphia, Pa., a corporation of Pennsylvania ApplicationFebruary 25, 1957, Serial No. 642,214

8 Claims. (Cl. 20G-38) This invention relates to rotary drum limitswitch operating mechanism and has for an object the provision ofimprovements in this art.

The invention has been developed in connection with limit switchoperating mechanism for metal forming presses and will be discussed inthis connection though without intention of limiting the eld of use ofthe invention in any way.

As is well known, forming presses of the rotary shaft type haveassociated with them a limit switch control mechanism for accuratelycontrolling the actions of .various parts of the press as well asvarious related devices such as feeders and ejectors (broadly referredto as servers) which must operate in accurately timed relationship withthe press. These limit switch control mechanisms generally comprise agroup of adjustable cams carried on a rotary cam shaft and acorresponding group of limit switches carried `by a casing or shellsurrounding the cams and operated 'by the cams.

It can be seen that it is difcult to gain access to the cams foradjustment and this is a great disadvantage, for in many types ofoperations, as when changing from the stamping of one part to another,frequent resetting of the cams is necessary.

Another ditiiculty encountered with the usual limit switch operatingmechanisms is that there is exposure to live contacts in makingadjustments so that an electrician as well as a press setter is requiredto make adjustments.

According to the present invention the limit switches are mounted at aninterior location and an outside rotary drum carries all of the cams foroperating the limit switches. The mechanism is so designed that all camsetings and adjustments can -be made from the outside of the drum andconsequently there is no danger of exposure to live contacts. Neither isthere any need to manipulate any parts related to an electrical circuit.Therefore there is no need to have an electrician on the job whensetting up operations. Another benefit of the arrangement is that theenclosed mechanism permits with safety the use of switches of heavycurrent capacity so that it is lnot necessary to use low current limitswitches which act through high current relays, as is required when contacts are exposed during adjustment.

The apparatus includes means for installing parts to give an unlimitedselection of cam action by inserting or rearranging or removing standardparts.

The apparatus also includes means for obtaining a vernier or micrometeradjustment of the end of the cam and this independently for either end.

The apparatus also provides clearly visible scales which indicate theselected cam arrangement so this can be noted and recorded for futurereference, as for example for a later rapid resetting to perform thesame operations.

The apparatus also provides means for making all cam settings andadjustments wholly by manipulation of parts which are provided andwithout the use of any Y tools whatever.

The objects and advantages of the invention will be apparent from thefollowing description of an exemplary embodiment, reference being madeto the accompanying drawings thereof, wherein:

Fig. l is a vertical axial section through one form of `apparatusembodying the invention;

Fig. 2 is a vertical transverse section taken on the line 22 of Fig. l;

Fig. 3 is a flat developed plan View ofthe outer surface of the rotarydrum, some of the cam element units lbeing shown in section, to showwhat the action will be in one complete rotation of the drum;

Fig. 4 is an enlarged partial transverse vertical section showing a camhaving a Vernier adjustment at one end, the view being taken on the line4-4 of Fig. 5;

Fig. 5 is a partial flat projection of the parts shown in Fig. 4 as seenfrom the line 5-5 on Fig. 4;

Fig. 6 is a perspective View of the apparatus with a protective outercover in place, parts of the outer cover being cut away to show therotary drum within; and

Fig. 7 is a transverse section in perspective, the section beingindicated by the line 7-7 in Fig. 1.

As shown in the drawings, the apparatus comprises a base 1i) which isadapted to be mounted in any convenient position, as on a press forexample. At one end the base carries a pedestal support 11 on whichthere issecured, as by cap bolts 12, an insulating support bar 13 onwhich there are mounted a plurality of limit switch units 14. As shownin Figs. 2 and 4, each limit switch comprises a pair of fixed contacts15 and 16 and a closure member 17 which is pivotally ,mounted on a shaft18 carried by a support 19 on the insulating support bar 13. The pivotedclosure member has an extension carrying an operating roller 20 adaptedto 'be operated by a rotary cam. Conductor leads 21 extend from thecontacts 15, 15 into a conduit 2.2 secured in the Ypedestal support 11whence they run to their appropriate connections. The closure member 17is urged toward contact engaging or circuit closing position by a spring23.

At the outer end of the base 10 there is carried another pedestalsupport 26 which carries a bearing v2'1' in which a driven drum shaft 28is rotatably mounted. The shaft carries a head 29 which comprises partof a rotary cam drum 3i). For rigidity the end of the drum isrotatablysupported on an annular bearing ange 31 carried by the pedestal support11, a sealing and friction-reducing ring 32, as of nylon or Teflon beinginterposed 'between the flange 31 and the inner surface of the drum. Atthe other end the insulating bar 13 has abearing cup 33 secured thereon,as vby cap bolts 34, and within this bearing cup there is rotatablymounted a hub 3'5 of the ead 29, a sealing and friction reducing ring 36as of nylon or Teon being interposed.

The drum in a plurality of axial positions corresponding to the limitswitch positions is provided with a plurality of circumferential slots4t) separated by bars 41 of the drum providing for the arrangement ofoperating cams over any part or all of the complete circumference. Oneach side of each slot zone there is provided a circumferential line oftapped holes 42 to receive screws 43 provided with knurled heads 44 formanual manipulation. The screws are adapted to secure L-shaped camsector units 45 to the drum. The lower portion of a cam sector unit isbent7 as at 45a, to present a widened surface to the switch cam roller2' but there is suflicient Width in the slot for two of the bentportions 45a to enter side by side. The cam roller is made ofdielectricmaterial or is insulated.

The screw holes 42 on opposite sides of a slot are staggered relative toeach other so that the cam units can have an overlap to obtain a totallength of cam operating surface which is other than a multipleof the camsector units. As shown, the screw holes 42 are placed l0 defr greesapart so that the full circumference is divided into 36 equal spaces andthere is a 5 degree offset between the holes of adjacent rows. The camsegments shown herein have an extent of 2O degrees and by an end overlapa length range from l5 degrees down to 5 degrees can be obtained. Itwill be observed that the cam units are cut away on the ends, as at 45h,so as to meet at thc connecting bars 41. While the cam units selectedfor illustration herein have a circumferential length of 2() degrees,they could be either longer or shorter but preferably are some multipleof the screw hole spacing.

At either end where there is need for a more precise length adjustmentmeans are hereby provided for moving the end cam sector unit with amicrometer or Vernier control. This arrangement is shown in Figs. 4 and5. Here the sector in the top arm which is clamped to the drum isprovided with a circumferential slot 45C to receive the clamp screw 42.At one end an upturned projection 45d is apertured or slotted from theend to receive a grooved head 48 of a Vernier adjusting screw 49threaded in a short shaft 56 turnably carried in the upturned ears of ananchor screw 5l threaded in one of the holes 42. A knurled head 52 isthreaded on the adjusting screw 49 after it has been screwed in theshort shaft 50 and is secured thereon by a drive pin 53. It will be seenthat the grooved head can be entered in the slot of the upturned portion45d after the anchor screw has been screwed into the drum. If theVernier arrangement is not desired the slotted cam segment can be movedby hand and clamped by the screw 43.

The drum 30 is provided with a marked scale 55 at one or more points asdesired to provide a reading of the cam arrangements. This may be readand recorded for future reference.

The entire apparatus is enclosed by a dust proof cover 56 which isremoved while making adjustments. and replaced to protect the operatingapparatus after the adjustments have been made.

The operation and adjustment of the apparatus will be apparent from theabove description. By providing an ample supply of the Vstandard camsegment units and clamp screws and the Vernier segment units and Vernieradjustment units it will be a simple matter for a mechanic to arrangecams of any length and number desired for each limit switch and thusprovide any type of interrelated control which may be desired.

While one embodiment has been described in detail for purposes ofillustration it is to be understood that there may be variousembodiments and modifications within the general scope of the invention.

What is claimed is:

l. Rotary limit switch operating apparatus, comprising in combination, axed inner support, a limit switch mounted on said support and providedwith a cam follower adapted to be operated by a circumferentially movingcam, a cam drum mounted for rotation around said switch and its camfollower, said drum being provided with circumferentially elongatedslots separated by short connecting elements, a plurality of cam units,each having a circumferentially extending cam segmentdisposed in acircumferential slot and a part lying outside the drum, a plurality ofcircumferential cam segments Vtogether forming a circumferentialcomposite cam for actuating said cam follower, and means securing thecam units by their outside elements to the drum.

2. Rotary limit switchV operating apparatus, comprising in combination,a fixed inner support, a limit switch mounted on said support andprovided with a cam follower adapted to be operated by acircumferentially moving cam, a cam drum mounted for rotation aroundsaid switch and its cam follower, said drum being provided withcircumferentially elongated slots separated by short connectingelements, a plurality of cam units, each having a circumferentiallyextending cam segment disposed -in a circumferential slot and a partlying outside the drum, a plurality of circumferential cam segmentstogether forming a circumferential composite cam for actuating said camfollower, and means securing the cam units by their outside elements tothe drum, said composite cam comprising some segments which overlap eachother circumferentially to provide a total circumferential cam lengthwhich is other than a multiple of the total lengths of the cam segmentsof which it is composed.

3. Rotary limit switch operating apparatus, comprising in combination, afixed inner support, a limit switch mounted on said support and providedwith a cam follower adapted to be operated by a circumferentially movingcam, a cam drum mounted for rotation around said switch and its camfollower, said drum being provided with circumferentially elongatedslots separated by short connecting elements, a plurality of cam units,each having a circumferentially extending cam segment disposed in acircumferential slot and a part lying outside the drum, a plurality ofcircumferential cam segments together forming a circumferentialcomposite cam for actuating said cam follower, and means securing thecam units by their outside elements to the drum, said cam units beingL-shaped with a first arm of the L being blade-shaped to enter a slotfrom outside and with the second arm lying over the outer surface of thedrum alongside the slot, and means for securing said second arms of saidcam units to the drum.

4. Rotary limit switch operating apparatus, comprising in combination, afixed inner support, a limit switch mounted on said support and providedwith a cam follower` adapted to be operated by a circumferentiallymoving cam, a cam drum mounted for rotation around said switch and itscam follower, said drum being provided with circumferentially elongatedslots separated by short connecting elements, a plurality of cam units,each having a circumferentially extending cam segment disposed in acircumferential slot and a part lying outside the drum, a plurality ofcircumferential cam segments together forming a circumferentialcomposite cam for actuating said cam follower, and means securing thecam units by their outside elements to the drum, said cam units beingl-- shaped with a lirst arm of the L being blade-shaped to enter a slotfrom outside and with the Second arm lying over the outer surface of thedrumY alongside the slot, and means for securing said second arms ofsaid cam units to the drum, the means for securing said second arms ofthe cam units to the drum comprising screws threaded into holes in thedrum, the screwV holes being located on both axial sides of a slot andbeing Varranged in circumferentially staggered relationship on oppositesides of the slot.

5. Rotary limit switch operating apparatus, comprising in combination, afixed inner support, a limit switch mounted on said support and providedwith a cam follower adapted to be operated by a circumferentially movingcam, a cam drum mounted fory rotation around said switch and its camfollower, said drum being provided Vwith circumferentially elongatedslots separated by short connecting elements, a plurality of cam units,each having a circumferentially extending cam segment disposed in acircumferential slot and a part lying outside the drum, a plurality ofcircumferential cam segments together forming a circumferentialcomposite cam for actuating said cam follower, and means securing thecam units by their outside elements to the drum, said cam units being L-shaped with a first arm of the L being blade-shaped to enter a slot fromoutside and with the second arm lying over the outer surface of the drumalongside the slot, and means for securing said second arms of said camunits to the drum, at least some of the cam units being provided withcircumferentially elongated slots in their second arms which lie on theoutside of the drum, and screws entering holes and slots in said secondarms and being threaded in holes of the drum for-securing the cam unitsto the drum.

6. Apparatus as set forth in claim 5, which further includes Vernieradjusting means for an end cam segment unit, the said end cam segmentunit having a circumferential slot, a clamp screw threaded in the drumthrough the unit slot for securing the unit to the drum, an upstandingslotted member on said end unit, a Vernier screw carried by a shaft on astud screw threaded in another hole in said drum, a grooved head on saidVernier screw embracing said upstanding slotted member, and a removableknurled operating thumb head secured as by a drive pin on the other endof the Vernier screw.

7. Rotary drum limit switch operating apparatus, comprising incombination, a pedestal support, a support bar carrying a limit switchcarried by said pedestal support, a second pedestal support spacedaxially from the first said pedestal support, a rotary drum having ashaft rotat- 6 ably carried by said second support, adjustable camoperators carried by said drum which are insertable and adjustable fromthe outside, and rotary bearings between the outer end of the drum andthe first pedestal support and between the outer end of the support barand the second pedestal support.

8. Apparatus as set forth in claim l, wherein a plurality of switchesare mounted in axially spaced relationship within said drum and whereinsaid drum is provided with a plurality of axially spaced slots and aplurality of composite cams for operating said plurality of switches.

References Cited in the file of this patent UNITED STATES PATENTS2,692,534 Pluess Oct. 26, 1954

